JavaScript Notes (4)

Aug 5 posted in Web (RSS), comments.

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Practical sense of this small function used in web development on quite a lot less to do with the background timer: (retarder)

To specify a specific period of time after the implementation of certain procedures.

setTimeout (): (1.0 version)
Format:
[Timer object name =] setTimeout ("<expression>", ms)
Function: The Executive <expression> time.
Example 1:

<Script>
    function count() {
        setTimeout("alert(' Three seconds to  ')",3000)
    </Script>
    <INPUT TYPE="button" VALUE="  Countdown begins  ">

Example 2:

    <Script>

    function show() {
        document.all['news'].style.display = "";
        setTimeout("hide()",500);
    }

    function hide() {
        document.all['news'].style.display = "none";
        setTimeout("show()",500);
    }

    </Script>

    <Body onload="show()">
     Latest news  :<FONT> Ambush  ...</FONT>
    </Body>

clearTimeout (): Termination Timer

Format:

clearTimeout (timer object name)

setInterval (): (1.2 version)

Comparison of this function have feelings. Previous projects have used jQuery, that is the main use of this function.

Format:

[Timer object name =] setInterval ("<expression>", ms)

Function: Repeat the <expression>, up to the window, the frame is closed or the Executive clearInterval.

clearInterval (): Termination Timer

Format:

clearInterval (timer object name)

Example 1:

    <Script>

    var sec = 0;
    timerID = setInterval("count()",1000);

    function count() {
        num.innerHTML = sec++;
    }

    </Script>

     Residence time  :
    <FONT FACE="impact">0</FONT> Seconds  
    <INPUT TYPE="button" VALUE=" Stop  ">

Example 2:

    <Script>

    var str = " This is an online auction Web site, please enjoy shopping!  !";
    var seq = 0;

    function scroll() {
        msg = str.substring(0, seq+1);
        banner.innerHTML = msg;
        seq++;
        if (seq >= str.length) seq = 0;
    }

    </Script>

    <Body onLoad="setInterval('scroll()',500)">
    <FONT></FONT>
    </Body>

This is a very beautiful --------------------< dividing line >--------------------

Image object:

Images on the page will automatically be seen as the image object, and according to the order, respectively for the document.images [0], document.images [1] ...
This is important, which also do not understand why sometimes write id or name, can find the picture!

The establishment of the image object:
Format:
Image Object Name = new Image ([width], [height]) / / px

Image object properties:
border complete height hspace lowsrc name src vspace width

Image object events:
onAbort onError onKeyDown onKeyPress onKeyUop onLoad

Example 1: (pre-set)

   <Script>

    img0 = new Image();
    img0.src = "images/snow0.gif";

    img1 = new Image();
    img1.src = "images/snow1.gif";

    document.write (" Already read two map files, but does not display  .");

    </Script>

Example 2:

   <Script>
    function img-preload(idx){
        eval("img"+idx+" = new Image()");
        eval("img"+idx+".src = 'images/snow"+idx+".gif'");
    }

    img-preload(0);
    img-preload(1);
    document.write (" Already read two map files, but does not display  .");

    </Script>

Example 3:
<Script>
function img-preload (imgname, idx) (
eval ("img" + idx + "= new Image ()");
eval ("img" + idx + ". src = 'images /" + imgname + ". gif'");
)

img-preload ("snow0", 0);
img-preload ("snow1", 1);
document.write ("already read the two map files, but does not appear at this time.");

</ Script>

This is a very beautiful --------------------< dividing line >--------------------

About the contents of this primary for my JavaScript is not useful,
When looking at these pictures on

Navigator object: (pilot)

Detect browser version, supported by the MIME type of the installed plug-ins (plug-in). The object contains two sub-objects: external object, MIME type object.

Navigator object properties:

Format: navigator. Attribute

Example 1:

<Script>

with (document) {
    write (" Your browser information  :<OL>");
    write ("<LI> Code  :"+navigator.appCodeName);
    write ("<LI> Name  :"+navigator.appName);
    write ("<LI> Version  :"+navigator.appVersion);
    write ("<LI> Language  :"+navigator.language);
    write ("<LI> Compile platform  :"+navigator.platform);
    write ("<LI> User table header  :"+navigator.userAgent);
}

</Script>

Example 2:

<Script>

if (document.all) {
   document.write(" Your browser is  :MSIE");
}   else {
   document.write(" Your browser is  :Navigator");
}

</Script>

plugin object's attributes:
Format: navigator.plugins. Attribute

Example:

  <Script>
    var len = navigator.plugins.length;
    with (document) {
        write (" Your browser has support for "+ len +"  plug-in:<BR>");
        write ("<TABLE BORDER>")
        write ("<CAPTION>PLUG-IN  Inventory  </CAPTION>")
        write ("<TR><TH> <TH> Name  <TH> Description  <TH> File name  ")
        for (var i=0; i<len; i++)
            write("<TR><TD>" + i +
                "<TD>" + navigator.plugins[i].name +
                "<TD>" + navigator.plugins[i].description +
                "<TD>" + navigator.plugins[i].filename);
    }

    </Script>

mimeType object's attributes:
Format: navigator.mimeTypes. Attribute

Example:

<Script>
var len = navigator.mimeTypes.length;
with (document) {
    write (" Your browser has support for "+ len +"  MIME Type  :");
    write ("<TABLE BORDER>")
    write ("<CAPTION>MIME type  Inventory  </CAPTION>")
    write ("<TR><TH> <TH> Name  <TH> Description  <TH> Extension  <TH> Note  ")
   for (var i=0; i<len; i++) {
       write("<TR><TD>" + i +
           "<TD>" + navigator.mimeTypes[i].type +
           "<TD>" + navigator.mimeTypes[i].description +
           "<TD>" + navigator.mimeTypes[i].suffixes +
           "<TD>" +
          navigator.mimeTypes[i].enabledPlugin.name);
}
}
</Script>